A small-size dual-plane EBG microstrip lowpass filter with a U-shaped microstrip line geometry

A novel small-size dual-plane electromagnetic band-gap (EBG) microstrip lowpass filter with a U-shaped microstrip line geometry is proposed in this paper. With this unique geometry of the microstrip line and the dual-plane arrangement of EBG structures, the proposed structure achieves a flat and deep stopband up to 10 GHz with high selectivity within a small circuit area. Its ripple level in the passband is well tailored by employing the Chebyshev distribution to taper the dimension of EBG cells in the ground plane. This novel filter design is implemented using standard fabrication process. The measured results are in good agreement with the simulated results displaying an excellent filtering functionality of the proposed lowpass filter. The proposed structure provides a new approach to design a high performance compact microstrip lowpass filter for microwave circuits. It provides additional flexibility to the circuit layout design due to the U-shaped microstrip line geometry.